Since the first broadcast, music on the radio in the United States has been a cultural battleground. It's been a place where people who wanted to shape the nation’s society skirmished over what America should sound like, and should be like.

One out of five radio stations today plays country music. But the story of how country music got its hold on the nation is an unlikely one. When radio reigned, America tuned in to a much different sound: “respectable” music, high-quality broadcasts with a sophisticated, big-city sound. But a lot of Americans didn’t want to listen to music dictated by New York’s cultural elite.

Radio’s golden age started in the late 1920s. Big networks like CBS, NBC and Mutual armed themselves with the best on-air talent and finest musicians, had powerful allies in Washington, and pushed smaller radio operations out of business. And then in the late 1940s, they just walked away, which left radio wide open for other voices. Radio once again became a cultural battleground.

See the growth of AM and FM stations in the United States from 1922 through 2006.

Related American RadioWorks documentaries:Radio Fights Jim Crow
During the World War II years a series of groundbreaking radio programs tried to mend the deep racial and ethnic divisions that threatened America